Further tweaks for connect migration:

- If no connections exist in IndexedDB during the migration, there is no
  need to attempt to even hit the secure backend. This now removes the
  keychain requests on fresh installs.
- If the 1.20.0-beta.0 migration errors, we don't leave the user on the
  loading screen. They just won't have new connections and loading will
  continue.

Author: durran